Evaluation of negative differential mobility in low-density polyethylene from charge packet motion before and after short circuit

The electric-field-dependent mobility of charge carriers in low-density polyethylene (LDPE) is experimentally investigated using the pulsed electroacoustic (PEA) method. Positive charges are injected from a semiconductive electrode under a 30 kV DC field, forming a localized charge packet. The system is short-circuited 15 minutes after the application of the high DC field to measure space charge behavior over a wide range of electric fields. Space charge and electric field distributions are used to determine the effective mobility. The effective mobility decreases exponentially with increasing electric field and is accurately described by the Gaussian disorder model. These results provide new experimental evidence of negative field-dependent mobility in LDPE and contribute to a better understanding of charge transport mechanisms in polymeric dielectrics under high electric fields.